Porous graphite: A facile synthesis from ferrous gluconate and excellent performance as anode electrocatalyst of microbial fuel cell

A porous graphite (PG) is proposed as anode electrocatalyst of microbial fuel cell (MFC), which is synthesized by thermally decomposing ferrous gluconate followed by leaching iron. The physical characterizations from scanning electron microscopy, Brunauer-Emmett-Teller, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, indicate that the resulting PG is mesopore-rich and exhibits high graphitization with oxygen-containing functional groups. When evaluated on a naked carbon felt (NCF) anode, the resulting PG provides the MFC based on Escherichia coli with excellent power output. The MFC using the carbon felt anode loaded with 3.0 mg cm⁻² PG delivers a maximum power density of 2.6 W m⁻², compared to the 0.2 W m⁻² for the MFCs using NCF anode. This excellent performance is attributed to the electronically conductive graphite and porous structure of the resulting PG. The former provides the anode with high activity towards redox reactions of c-type cytochromes in bacteria, the latter stimulates bacteria to produce their flagella that help bacteria to firmly bond each other.